This invention relates to surgical instruments, and in particular to powered arthroscopic surgical instruments.
Powered arthroscopic surgical instruments typically include a rigid, stationary outer tube within which a rigid inner tube is rotated by a motor. A cutting implement, such as a blade or abrading burr, is disposed on the distal end of the inner tube. Tissue or bone is exposed to the cutting implement through an opening in the distal end of the outer tube, and tissue or bone fragments cut by the rotating blade or burr are drawn through the interior of the inner tube along with irrigating fluid by the use of suction applied at the proximal end of the instrument. Examples of such surgical instruments are described in U.S. Pat. Nos. 4,203,444, 4,274,414, 4,834,729, and 4,842,578, all of which are assigned to the present assignee.
Some arthroscopic surgical instruments are linear, that is, straight between their proximal and distal ends. Others are curved to facilitate positioning the cutting implement against tissue to be cut without requiring that the instrument be removed from the body and reinserted through an additional puncture. In a curved instrument, a region of the inner tube is flexible to enable the inner tube to accept the curvature imposed by the outer tube while transmitting the torsion applied by the motor to the blade. In both cases, the user changes the orientation of the cutting implement by rotating the instrument.